The present invention pertains to a radiation shielding apparatus for a radio transmitting device. More particularly, the present invention pertains to a radiation shielding apparatus for protecting a user from radiation generated by a hand-held cellular phone.
It is well known to shield circuitry from electromagnetic wave radiation by providing a layer of electromagnetic wave shielding material between an electromagnetic wave source and circuitry to be protected. Conventionally, such shielding is provided to prevent the influence of electromagnetic wave noise from affecting the protected circuit.
Cellular radio telephones have recently become well known devices. A cellular radio telephone is generally a portable unit for communication over hard wire phone lines by transmitting electromagnetic wave signals between the mobile cellular phone and stationary transmission/reception units known as "cells". These cells are connected with the hard wired telephone network, usually through a direct mechanical link. Thus, a user of a cellular phone is not confined by the traditional limitations of being mechanically linked with the hard wired telephone network. Rather, the user of a cellular phone has mobility due to the radio transmission of the electromagnetic wave signals between the cellular phone and the cells, and is able to communicate via the hard wired telephone network as long as the cellular phone is within range of an appropriate cell.
The cellular frequency typically used is between 800 and 900 megahertz. In other words, in order to communicate via the cellular telephone, the cellular telephone receives electromagnetic wave radiation in the frequency range between 800 and 900 megahertz from a cell, and also transmits electromagnetic wave radiation at this frequency range to the cell.
The transmission from the portable cellular telephone is traditionally accomplished through an antenna. In one configuration of a cellular telephone, known as a car phone, the transmitting/receiving unit is fixed at a location in the car, usually the trunk. The antenna in this configuration is fixed to the exterior of the car to facilitate reception and transmission of electromagnetic wave signals. The car phone also has a hand set disposed at an accessible location for the user. Usually, the hand set is disposed in the passenger cabin and is mechanically and electrically linked to the antenna by a mechanical and electrical link with the transmitting/receiving unit of the car phone. Thus, in this configuration the user has minimal exposure to the electromagnetic waves generated by the car phone. The transmitting/receiving unit of the car pone, which may be a source of electromagnetic wave radiation exposure, is at a relatively safe distance from the user in the trunk. The antenna of the car phone, which transmits the electromagnetic wave radiation, is also at a relatively safe distance at a portion of the exterior of the car. Furthermore, the metal construction of the car acts to shield the user from the electromagnetic wave radiation.
In another configuration of a cellular phone, known as a transmobile phone, the transmitting/receiving unit is carried in a bag, and an antenna fixed to the transmitting/receiving unit transmits the electromagnetic wave radiation necessary for communication. Again, the hand set, which the user places against her head to hear and to speak, is disposed separate from the electromagnetic wave generating components of the cellular phone such as the transmitting/receiving unit and the antenna. Furthermore, when used within a car, a second antenna may be used which is disposed outside the vehicle to facilitate reception and transmission of the electromagnetic waves.
In a third configuration of a cellular phone, known as a hand-held cellular phone, the transmitting/receiving unit and antenna are provided in the interior and/or disposed on an outside surface of the handset. In other words, in the hand-held cellular phone, the transmitting/receiving unit, hand set (including a mouthpiece and an earpiece) and the antenna are provided in a single compact unit. This type of cellular phone has steadily increased in popularity because of the convenience and mobility afforded by its compact structure. Traditionally, these cellular phones transmit at a cellular frequency range between 800 and 900 megahertz and at a power any where from less than one to six or more watts.
When using the hand-held cellular phone, the user places the hand set to his head so that his ear is in contact with the earpiece, and his mouth is at a location close to the mouthpiece. The antenna, which usually extends from the top surface of the hand set, transmits and receives the electromagnetic wave radiation. It is also well known to provide an internal antenna within the hand set to make the hand-held cellular phone even more compact. The electromagnetic wave radiation transmitted by the antenna is generated by a transmitter disposed in the interior of the hand set. Therefore, the user is in close proximity to the source of transmission of electromagnetic wave radiation, and the head and brain of the user receives direct exposure of this electromagnetic wave radiation generated by the hand-held cellular phone.
FIG. 7 shows a typical configuration for a hand-held cellular phone, commonly known as a "flip phone". This conventional cellular phone has a main phone body 1 having an earpiece 2 disposed thereon. A mouthpiece 3 shown in the closed position is flipped downward so that when the hand-held cellular phone is appropriately positioned by a user, the earpiece 2 is adjacent to the user's ear, while the mouthpiece 3 is adjacent to the user's mouth. An antenna 4, which may be telescoping or fixed, is disposed externally on the phone body 1. Alternatively or additionally, an antenna 4 may be internally disposed. The antenna 4 emits electromagnetic wave radiation to send communication signals from the hand-held cellular phone to a distant cell of a cellular network and receives electromagnetic radiation carrying communication signals from the cell. Thus, the user is able to communicate through the cellular network to the hard wire telephone network.
However, as shown in FIG. 8, internal radiation emanating components 5, and the external antenna 4 emit radiation which exposes the user to the health risks now being associated with exposure to electromagnetic wave radiation in the cellular frequency band. Furthermore, it is possible that the electromagnetic wave radiation emanating from the hand-held cellular phone or some other emanating radiation from the hand-held cellular phone is causing the recently observed health problems. However, at the present time the exact cause of the health risks is not known. But, it is apparent that there is great demand for a means to shield the users of hand-held cellular phones from unwanted, and possibly harmful, exposure to the radiation generated by the cellular phone.
The extent of the danger seems to be as yet not known. In fact, there seems to be a deficiency in research on health effects of electromagnetic fields, particularly those emitted by portable phones in the cellular frequency band-800 to 900 millions of cycles per second or megahertz. The cellular phone industry has done studies which target the thermal effects of electromagnetic fields. However, apart from thermal effects, recent tests have shown that radio waves around the cellular frequency band can damage the resilient bloodbrain barrier, which protects the brain from toxins. Furthermore, radio frequencies, including the European cellular frequency, have been shown to damage the calcium coating in cells that regulates the passage of hormonal "messages" between cells. Some scientist believe that the brain tissue absorbs some of the power of the electromagnetic radiation. The exact empirical health risks which can be directly linked to the cellular phone are still not known. However, it is apparent that the users and future purchasers of cellular phones are demanding a means to protect themselves as much as possible from exposure to the radiation generated by the cellular phone.
Very recently, serious questions have arisen regarding the safety of users exposed to the cellular phone electromagnetic wave radiation. It has also been suggested that such exposure, particularly due to the use of a hand-held cellular phone, has contributed to the occurrence of cancer and brain tumors in the brains of users of cellular phones. It has recently been speculated that the electromagnetic wave radiation transmitted by the hand-held cellular phone has a detrimental effect on the blood-barrier when a user is exposed to electromagnetic wave radiation around the cellular frequency. It has further been suggested that the electromagnetic wave radiation generated by the cellular phone has a detrimental effect on calcium contained by body cells and disrupts the functioning of such cells. These serious concerns have prompted widespread consternation by users of cellular telephones. In fact, due to the concern over the effects of exposure to the electromagnetic wave radiation generated by the cellular phone, the future of the "wireless` communication industry has very recently been questioned.
Therefore, there is an urgent need in the cellular telephone art to provide a means for protecting users of cellular phones, particularly, hand-held cellular phones, from unnecessary and possibly harmful exposure to the electromagnetic wave radiation generated by the cellular telephone. However, the conventional art merely provides electromagnetic wave shielding to protect internal circuitry from the noise influence of background radiation. There is no conventional device which is effective for protecting a user of cellular phones from unwanted exposure to electromagnetic wave radiation generated during use of the cellular phone.